Old Lyme — Getting to spend their work day at Griswold Point, where great white egrets, lighthouses and acrobatic least terns adorn lapping marine waters, is a special experience in its own right.

But on Monday, the Nature Conservancy’s four LEAF interns and their mentor, Katie Ristau-Estes, had a rare encounter of hushed awe at the preserve, where the Connecticut River meets Long Island Sound.

“Ooh,” said Giana Vargas, a 17-year-old high school senior, as Griswold Point naturalist and warden Miranda Vogt led her beside a humble cluster of gray stems and grass that served as a cradle for a newborn piping plover. “It’s so tiny.”

Vogt found the newborn plover nestled beside the as-yet unhatched egg of its sibling a few feet behind a section of the preserve the four interns were helping to rope off that morning. The simple barrier marks the sandy area just above the high tide line where the eight pairs of plovers and about 30 pairs of least terns, both of which are threatened species in the state, are nesting this summer, reminding visitors to stay out.

“I really feel like I’m making a difference,” Vogt, a 21-year-old college senior studying conservation biology, told the five young women, after describing her daily duties at the preserve: picking up trash, asking kayakers, boaters and their dogs who land at the preserve to keep away from the birds, and keeping counts of the nesting pairs and chicks. “This area is closed to the public, and a lot of people don’t like it when they’re being restricted. But I feel like it’s up to me to be the guardian for these birds. My supervisor calls me the mother of these birds. On days I take off, I feel guilty, because when I come back I can see the dog footprints and the human footprints above the high tide line. Some people don’t care.”

The four interns, all from Connecticut cities, have been working since July 7 on various projects at conservancy preserves across the state, erecting fences, digging drainage trenches, filling potholes and building a trailer to transport equipment, all the while sharing housing and living expenses in a dormitory at Western Connecticut State University in Danbury. The month-long program for urban youth began about five years ago in Connecticut, but LEAF — Leaders in Environmental Achievement for the Future — began at the national offices of the conservancy about 20 years ago, said Cynthia Fowx, manager of conservation outreach and the conservancy’s Devil’s Den Preserve in Weston, one of the areas the interns worked this summer.

The program, she said, is designed to help prepare youth for college and careers in environmental fields, she said, and at the same time provide able hands for projects that need to be done.

“They’re doing work we’d have to pay someone else to do,” she said. The students chosen, she added, are all top achievers in environmental science programs at their high schools.

One of the interns, 19-year-old Janet Sakouvogui of New Haven, said she’s been learning a lot this summer, and has been enjoying discovering preserves around the state that she didn’t know about.

“It’s been a great experience,” she said, after retrieving a broken fishing pole with a tangle of monofilament line out of the dunes at Griswold Point, removing a common source of wildlife injury. “I feel like they were hiding these places from us.”

Vargas, part of a large family at her home in Waterbury, said the internship has fostered her interest in environmental studies, and helped her to learn to be more independent.